The present invention relates in general to cyclone separators for separating steam from water, in the steam drum of a boiler.
U.S. Pat. No. 2,271,634 to Fletcher discloses a cylindrical cyclone separator having a circular whirl chamber, a tangential inlet, a central steam outlet located at the top of the circular whirl chamber, and a water outlet located at the bottom of the whirl chamber. To prevent water from being discharged through the steam outlet, means are provided for increasing the downward component of the incoming stream of steam and water mixture. This means is a segmented plate having downwardly and rearwardly inclined edges that causes the incoming steam and water mixture to be deflected downwardly towards the water outlet of the separator.
U.S. Pat. No. 2,293,740 to Kooistra discloses a similarly designed cyclone separator that does not utilize the segmented plate but rather employs a bottom cup at the bottom of the whirl chamber which confines the steam to the upper portion of the whirl chamber and prevents it from passing down into the separated water as it discharges from the whirl chamber, into the drum.
U.S. Pat. No. 2,298,285 to Fletcher discloses another variation of the cylindrical cyclone separator this time employing a rim or cap on top of the cyclone separator steam outlet together with the segmented plate. The rim acts to enhance separation of water and reduction of pressure drop in the separator.
U.S. Pat. No. 2,321,628 to Rowand et al. discloses a cyclone separator which is closer in configuration to the present standard shown in FIG. 1 of the present application. The circulator whirl chamber in this reference is the frustum of a cone at the upper portion and substantially cylindrical at the lower portion where the water is discharged. Again, a tangential inlet is employed to deliver the steam water mixture into the cyclone separator, and is of a vertical extent substantially equal to that of the tapered portion of the whirl chamber. The tapered configuration acts to direct the entering steam water mixture into a slightly downward direction to prevent upward spread of the deflected water and enhance separation of the steam therefrom.
U.S. Pat. No. 2,346,672 to Fletcher discloses a substantially cylindrical cyclone separator this time having instead of a tangential inlet a large steam/water inlet which extends over a large fraction of the perimeter of the cyclone separator. As indicated in the reference, the inlet can extend to approximately ⅓ of the perimeter of the cyclone separator to provide adequate flow capacities. One object is to produce a separator or densifier which operates effectively with low pressure drop so that it can be advantageously used where only a small pressure head is available.
U.S. Pat. No. 2,395,855 to Fletcher discloses a substantially cylindrical cyclone separator having a tangential inlet and where the steam outlet center is located eccentric of the whirl chamber center to effect enhanced separation of steam from the water. This design also employs the segmented plate seen in the previously described patents.
U.S. Pat. No. 2,402,154 to Fletcher and the aforementioned U.S. Pat. No. 2,395,855 are both divisionals of the same application. The U.S. Pat. No. 2,395,855 is drawn to the particular type of fluid separator itself; while the U.S. Pat. No. 2,402,154 is drawn to the combination of this device in a steam generator.
U.S. Pat. No. 2,434,637 to Brister, U.S. Pat. No. 2,434,663 to Letvin and U.S. Pat. No. 2,434,677 to Stillman are all drawn to various aspects of the perforated cone used at the top of the cyclone separator to enhance separation of the steam from the water.
U.S. Pat. No. 2,532,332 to Rowand is drawn to the particular construction of the separators which today are generally considered as secondary scrubbers.
U.S. Pat. No. 2,732,028 to Coulter is also drawn to a cyclone separator device very similar to that employed at this time. The cyclone separator has the aforementioned frustoconical upper section and generally cylindrical lower section with a tangential steam water inlet located on the side of the frustoconical section. The overall emphasis of this reference is drawn to means of simplifying the construction for accessibility and repair of the elements located in the steam drum. This is accomplished by dividing the steam space in the drum into separate compartments, one or more of which are open to the water space of the drum into the necessary drum safety valves while one or more of the other compartments are open to the steam and water separators of the drum the saturated steam outlets. Partitions are used to accomplish this division and they are effective in maintaining the separation of the drum components during normal operation but are easily broken when the safety valves are opened.
U.S. Pat. No. 2,891,632 to Coulter is drawn to a cyclone steam separator quite similar to that disclosed in the earlier mentioned Fletcher patent (U.S. Pat. No. 2,346,672) with the exception that instead of the steam water inlet being located only approximately along ⅓ of the circumference of the separator, this cyclone separator has the entire circumference provided with an array of vanes that “slice” the incoming steam water mixture into thin sheets to enhance separation of the steam from the water.
U.S. Pat. No. 5,033,915 to Albrecht is also drawn to a cyclone steam separator. The cyclone separator is a modified version of the standard conical cyclone separator that provides a lower pressure drop than the standard conical cyclone for an equivalent number of or an equivalent steam capacity of the separators. The major modification of this separator is that the cyclone separator's tangential inlet has been lengthened by 3 inches. This increase in length increases the cyclone inlet flow area by 28%.
FIG. 1 is a side sectional view of a conventional cyclone separator which is in current use by the assignee of the present application.
The conventional cyclone separator is generally designated 4 and comprises a conical portion 8 to which a vertically elongated tangentially connected steam/water inlet 6 is connected. The inlet 6 corresponds in axial length to the axial length of the conical portion 8.
Cyclone separator 4 includes an upper cylindrical steam outlet 10 which, in use, is surrounded by a cap with a perforated cover (not shown).
A lower cylindrical water outlet 12, having a water outlet ring 14, is connected to the bottom of conical portion 8 for discharging water which has been separated from the steam/water mixture.
The conventional cyclone separator of FIG. 1 could be improved by decreasing its pressure drop without adversely affecting the capacitor of the separator.
FIG. 2 is a side sectional view of a cyclone separator 20 described in U.S. Pat. No. 5,033,915. The cyclone separator 20 includes a tangential inlet 26 which extends into the lower cylindrical portion 22 of the cyclone separator 20. Steam that passes through the cyclone separator 20 is discharged through the upper cylindrical steam outlet 30. A lower cylindrical portion 22 having a ring shaped water outlet 24, is connected to the bottom of conical portion 21 for discharging water which has been separated from the steam/water mixture. The width of the inlet 26 of the cyclone separator 20 is defined by tangential outer wall 28 and the inner edge 32 of an inner wall 34.